The invention relates to photoflash lamp units adapted for being mounted on or inserted within cameras or attachments associated therewith. More particularly, the invention relates to such units which are electrically activated.
A currently marketed photoflash unit of the aforementioned type is described in U.S. Pat. No. 3,894,226 (Hanson) and referred to as a flip-flash. The unit comprises a planar array of eight high voltage type flash lamps mounted on a printed circuit board with an array of respectively associated reflectors disposed therewith. The lamps are arranged in two groups of four disposed on the upper and lower halves, respectively, of the rectangular shaped circuit board. A set of terminal contacts at the lower end of the unit is provided for activation of the upper group of lamps, while a set of terminal contacts at the top of the unit is operatively associated with the lower group of four lamps. The application of successive high voltage pulses (e.g., 500 to 4000 volts from a piezoelectric source controlled by the shutter of a camera (in which the array is inserted) to the terminal contacts at the lower end of the unit causes the four lamps at the upper half of the array to be sequentially-ignited. The array may then be inverted and inserted into the camera to flash the remaining four lamps. The flip-flash and similar devices have proven to be very reliable in photographic applications. Additionally, such units are relatively inexpensive to produce and easy to operate, even for the novice photographer. Present day flip-flash units possess one inherent disadvantage, however. Most contain only eight or fewer lamps and are thus unable to adequately complement the number of photographs available in most of today's film packs. Many packs, particularly those for use in the currently popular pocket-type cameras, contain from 12 to 20 photographs each. If a photographer was desirous of shooting more than eight pictures requiring supplemental lighting from a single pack of film it was therefore necessary to purchase at least two of the aforedescribed flip-flash units. Not only did this requirement prove costly, but it also increased the number of items which the photographer was required to carry.
It is believed therefore that a photoflash lamp unit which provides considerably more than eight flashes per unit, is relatively inexpensive to produce, and can be easily operated by even the novice photographer would constitute a significant advancement in the art.
From the following description, it will be further understood that the lamp unit of the invention, like the above flip-flash, is able to substantially eliminate the occurrence of the photographic phenomenon known as "red-eye". When the flash lamps are close to the camera's lens axis, such as within a few inches, and especially with the small pocket cameras, there is a tendency for an undesirable "red-eye" effect to occur (e.g., a red coloring of the pupils of persons in the picture). This results from the flash of light entering the subject's pupils and illuminating the retinas in the eyes at regions approximately in line with the optical axis of the camera's lens, so that the illuminated red coloring of the retina shows in the picture and causes the person's pupils to appear red. As stated, the photoflash lamp unit of the instant invention substantially eliminates this undesirable occurrence.